make non-prompt file references non-readonly by default (#239138)

[prompts]: make non-prompt file references non-readonly by default

src/vs/workbench/contrib/chat/browser/chatAttachmentModel/chatInstructionAttachmentsModel.ts

@@ -30,13 +30,13 @@ const toChatVariable = (
 	reference: Pick<IPromptFileReference, 'uri' | 'isPromptSnippet'>,
 	isRoot: boolean,
 ): IChatRequestVariableEntry => {
-	const { uri } = reference;
+	const { uri, isPromptSnippet } = reference;
 
 	// default `id` is the stringified `URI`
 	let id = `${uri}`;
 
 	// for prompt files, we add a prefix to the `id`
-	if (reference.isPromptSnippet) {
+	if (isPromptSnippet) {
 		// the default prefix that is used for all prompt files
 		let prefix = 'vscode.prompt.instructions';
 		// if the reference is the root object, add the `.root` suffix
@@ -57,7 +57,7 @@ const toChatVariable = (
 		enabled: true,
 		isFile: true,
 		isDynamic: true,
-		isMarkedReadonly: true,
+		isMarkedReadonly: isPromptSnippet,
 	};
 };